The invention relates to cleaning compositions and methods of cleaning surfaces with non-corrosive cleaning compositions. In particular, the invention relates to metal cleaning compositions useful in the cleaning articles or surfaces, including soft metal articles or surfaces.
Many commercial and domestic articles include surface layers comprising alkaline-sensative metals, for example aluminum or aluminum containing alloys. Such articles are known to those skilled in a variety of occupations or domestic activities, particularly those working in industrial plants, maintenance and repair services, manufacturing facilities, kitchens, restaurants and the like. The types of equipment which can have surface layers including aluminum include, without limitation, sinks, cookware, utensils, surfaces, for example, machine parts, vehicles, tanker trucks, vehicle wheels, work surfaces, tanks, for example soak tanks, hot tanks, immersion vessels (with or without agitators), spray washers (continuous or batch), and ultrasonic baths.
Aqueous alkali cleaners are known as effective cleaning agents. However, many such alkali cleaners have disadvantages when used on alkaline-sensative metals, for example aluminum. One particular disadvantage of using aqueous alkali systems to clean metal surfaces is the potential to corrode or discolor the surfaces. It is difficult to obtain an aqueous detergent solution at an effective pH to remove the soils, such as greases and oils, which often contaminate metal surfaces, and which would not be corrosive to the metal substrate. While aqueous cleaning solutions having a high pH are often more corrosive than aqueous solutions having a relatively low pH, corrosion and discoloration can still be problematic with the more mild solutions.
Various corrosion inhibitors are known and have been used to prevent corrosion of surfaces that come into contact with aqueous alkaline solutions. Some known corrosive inhibitors include the silicates, such as sodium silicate. Unfortunately, the sodium silicates begin to precipitate from aqueous solution at pHs below 11, thus, greatly reducing the effectiveness of these materials to prevent corrosion of the contacted surfaces when used in aqueous cleaning solutions having a lower pH. Additionally, when the silicate-containing compositions or their residues are allowed to dry on the surface to be cleaned, films or spots are often formed, which are visible and which are themselves very difficult to remove. The presence of these silicon-containing deposits can affect the texture of the cleaned surface, the appearance of the surface, and on cooking or storage surfaces, can affect the taste of the materials that come into contact with the cleaned surfaces.
It is also known to include calcium ions within cleaning composition to inhibit the attack of hydroxide ion on alkali sensitive metals. However, it has proven to be difficult to introduce calcium ions into alkaline cleaners without inducing precipitation of hydroxides of the calcium. This is especially true for highly alkaline solutions, such as concentrated solutions that are intended for dilution into use solutions. Theoretically, the protection against corrosion in such systems is based on the presence of the calcium ion in solution, so precipitation of the calcium ions adversely affects the corrosion inhibiting effectiveness of the system. Additionally, the formulations could not include strong chelating agents that could bind with the calcium ion, and again reduce the effectiveness of the calcium ion as a corrosion inhibiter.
Another problem that has been encountered with some such systems is that concentrates, which are formulated to be diluted into use solutions, tend to be sensitive to the use of dilution water with varying amounts of hardness. It has been found that when certain hard water is added, the additional level of calcium added to the cleaning solution can adversely affect the performance of the solution.
In accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in a first aspect, relates to a cleaning composition that includes at least one source of calcium ion; a source of alkalinity; a sequestering agent capable of complexing with calcium ion in an alkaline environment; a surfactant; and a water-soluble or water-dispersible acid-substituted polymer.
In a second aspect, the present application relates to a cleaning composition that includes a source of calcium ion; a source of alkalinity; a sequestering agent capable of at least partially complexing with calcium ion; and a surfactant selected from primary or secondary alcohol ethoxylate, secondary alkane sulfonate, alpha olefin sulfonate, linear alkyl benzene sulfonate, primary alcohol ethoxy carboxylate, sarcosinates, or mixtures thereof.
In a third aspect, the present invention relates to a cleaning composition that includes a source of calcium ion; a source of alkalinity; a sequestering agent capable of at least partially complexing with calcium ion; and a silicone-containing surfactant.
Another aspect of the present invention includes the cleaning composition of the first, second and third aspects described herein, such that the compositions are made by admixing the components with a solvent.
A further aspect of the present invention relates to a method of treating a metal surface with the cleaning compositions described in the first, second and third aspects, wherein the method includes applying the composition to the metal surface and removing the solution from the metal surface.
Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.